The perimeter of a montane bog at 1860 m elevation on northeastern Haleakala volcano was fenced in 1981 to provide protection from feral pig digging. This site had undisturbed native vegetation until introduced pigs arrived in the area some time after 1975 and extensively rooted the bog by early 1981. Prior to fencing, a large tract of vegetation, formerly a nearly intact turf dominated by Oreobolus, had been obliterated by pigs so that almost no vegetation cover remained. In a portion of the bog, the combined cover of native plant species increased from 6% to 95% after six years of protection. Most of the increase in cover, primarily by the dominant endemic sedges Oreobolus furcatus and Carex echinata and the grass Deschampsia nubigena, took place in the first three years after fencing. Recovery of non-dominants was incomplete after six years. Species which have failed to recover to pre-disturbance levels include Plantago pachyphylla, Argyroxiphium grayanum, and Calamagrostis expansa. Though they occur nearby, presence of alien plant species in the bog was minimal, and those present failed to increase their abundance, despite initially high levels of bare ground. In this instance, feral pig damage to the vegetation of an Hawaiian bog was largely reversible. This may be due to inherently low invasibility of native Oreobolus communities.

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